Method and article for concentrating fields at sense layers

ABSTRACT

A write line structure for a magnetic memory cell includes a write conductor having a front surface facing the memory cell, a back surface and two sides surfaces. A cladding layer is disposed adjacent a portion of the front surface of the write conductor, with the cladding layer terminating at spaced first and second poles adjacent the front surface of the write conductor. A data storage layer is operatively positioned adjacent the cladding layer. The distance between the poles is less than the width of the write conductor. The width of the data storage layer may be greater than or less than the distance between the poles.

THE FIELD OF THE INVENTION

The present invention generally relates to magnetic random access memory(MRAM) devices. More particularly, the present invention relates toferromagnetic cladding for concentrating a magnetic field at a senselayer.

BACKGROUND OF THE INVENTION

An MRAM device includes an array of memory cells. The typical magneticmemory cell includes a layer of magnetic film in which the magnetizationis alterable and a layer of magnetic film in which the magnetization isfixed or “pinned” in a particular direction. The magnetic film havingalterable magnetization may be referred to as a data storage layer orsense layer and the magnetic film which is pinned may be referred to asa reference layer.

Conductive traces (commonly referred to as word lines and bit lines) arerouted across the array of memory cells. Word lines extend along rows ofmemory cells, and bit lines extend along columns of memory cells.Because the word lines and bit lines operate in combination to switchthe orientation of magnetization of the selected memory cell (i.e., towrite the memory cell) the word lines and bit lines can be collectivelyreferred to as write lines. Additionally, the write lines can also beused to read the logic values stored in the memory cell.

Located at each intersection of a word line and a bit line is a memorycell. Each memory cell stores a bit information as an orientation of amagnetization. Typically, the orientation of magnetization in the datastorage layer aligns along an axis of the data storage layer that iscommonly referred to as its easy axis. External magnetic fields areapplied to flip the orientation of magnetization in the data storagelayer along its easy axis to either a parallel or anti-parallelorientation with respect to the orientation of magnetization in thereference layer, depending on the desired logic state (i.e., “1” or“0”).

The orientation of magnetization of each memory cell will assume one oftwo stable orientations at any given time. These two stable orientationsare referred to as parallel and anti-parallel, and represent logicvalues of “1” and “0”. The orientation of magnetization of a selectedmemory cell may be changed by supplying current to a word line and a bitline which intersect at the selected memory cell. The currents createmagnetic fields that, when combined, can switch the orientation ofmagnetization of the selected memory cell from parallel to anti-parallelor vice versa.

A selected magnetic memory cell is usually written by applyingelectrical currents to the particular word and bit lines that intersectthe selected magnetic memory cell. An electrical current applied to theparticular bit line generates a magnetic field substantially alignedalong the easy axis of the selected magnetic memory cell. The magneticfield aligned to the easy axis may be referred to as a longitudinalwrite field. An electrical current applied to the particular word lineusually generates a magnetic field substantially perpendicular to theeasy axis of the selected magnetic memory cell.

Preferably, only the selected magnetic memory cell receives both thelongitudinal and the perpendicular write fields. Other memory cellscoupled to the particular word line preferably receive only theperpendicular write field. Other magnetic memory cells coupled to thebit line preferably receive only the longitudinal write field.

The magnitudes of the longitudinal and perpendicular write fields areusually selected to be high enough so that the chosen magnetic memorycell switches its logic state when subjected to both longitudinal andperpendicular fields, but low enough so that the other magnetic memorycells which are subject only to either the longitudinal or theperpendicular write fields do not switch. The undesirable switching of amagnetic memory cell that receives only the longitudinal or theperpendicular right field is commonly referred to as “half-select”switching.

Manufacturing variation among the magnetic memory cells often increasethe likelihood of half-select switching. For example, manufacturingvariations in the longitudinal or perpendicular dimensions or shapes ofthe memory cells may increase the likelihood of half-select switching.In addition, variation in thickness or the crystalline anisotropy of thedata storage layers may increase the likelihood of half-selectswitching. Unfortunately, such manufacturing variations decrease theyield of manufacturing processes for magnetic memories and reduce thereliability of magnetic memories.

As with nearly every electronic device, it is desirable to reduce thesize and increase the package density of MRAM devices. However, a numberof factors influence the package density that can be achieved for anMRAM device. First, the size of the memory cells usually must decreasewith increasing package densities. Unfortunately, reducing the size ofthe memory cell can result in an increase of the magnetic field that isrequired to switch the magnetic orientation of the memory cell.

A second factor influencing the package density of an MRAM device is thesize of the write lines themselves. As with the memory cells, thedimensions of the write lines must typically decrease with increasedpackage density. However, reducing the dimensions of the write linesresults in a corresponding reduction in the current that can be carriedby the write lines. A reduction in current carried by the write linesresults in a weaker magnetic field at the selected memory cell andimpedes the ability to write the memory cell.

A third factor which influences the package density of an MRAM device isthe distance between a write line and an adjacent memory cell (e.g., amemory cell that is not the “selected” memory cell between theintersecting word and bit lines). As the distance between the writelines and adjacent memory cells decreases, the possibility increasesthat the magnetic field produced by a write line may inadvertently andadversely affect the information stored in an adjacent memory cell.

The problems associated with increasing the package density of an MRAMdevice have been addressed by others. For example, U.S. Pat. No.5,039,655 to Pisharody discloses the use of a superconducting materialaround the three sides of a write line that are not adjacent to a memorycell. The superconducting material effectively shunts the magnetic fieldcreated by the current in the write line and directs the magnetic fieldtoward the magnetic storage material of the memory cell. Similarly, U.S.Pat. No. 5,956,267 to Hurst et al., discloses a word line structure andmethod of manufacture therefore which improves upon the structure andconstruction methods of Pisharody.

One limitation of Pisharody and Hurst et al. is that the fluxconcentration means taught therein are restricted to three of the foursides of the write conductor. The maximum write field for a given writecurrent is thereby limited by the width of the write conductor. A writeline construction that overcomes this limitation and permits thecreation of a stronger magnetic write field for a given write line widthand/or a given current would be desirable.

Another limitation of Pisharody and Hurst et al. is that the fluxconcentration means which are formed around the write lines permit thecreation of both a longitudinal component of magnetic field in the senselayer of the memory cell, as well as a perpendicular component of themagnetic field. The perpendicular component of the magnetic field is atbest wasted in that it is unable to contribute to the orientation of thesense layer of the memory cell, and is perhaps harmful in that theperpendicular field may adversely affect adjacent memory cells. Thus, itwould be desirable in some instances to provide a write line structurein which the longitudinal field components are reinforced and theperpendicular field components are reduced or eliminated entirely.

SUMMARY OF THE INVENTION

The present invention provides a cladded write conductor for use in amagnetic random access memory device. The cladded write conductor of thepresent invention permits the creation of a stronger magnetic writefield for a given write line width and/or a given current.

In one embodiment, the write line structure for a magnetic memory cellcomprises a write conductor having a front surface facing the memorycell, a back surface and two sides surfaces. A cladding layer isdisposed adjacent a portion of the front surface of the write conductor,with the cladding layer terminating at spaced first and second polesadjacent the front surface of the write conductor. A data storage layeris operatively positioned adjacent the cladding layer. The distancebetween the poles is less than the width of the write conductor. Thewidth of the data storage layer may be greater than or less than thedistance between the poles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a schematic representation of a prior art magnetic fieldkeeper.

FIG. 1b is a greatly enlarged portion of the prior art magnetic fieldkeeper of FIG. 1a illustrating the components of the magnetic field inthe sense layer.

FIG. 2a is a schematic representation of an embodiment of the claddedwrite conductor of the present invention.

FIG. 2b is a greatly enlarged portion of the cladded write conductor ofFIG. 2a illustrating the components of the magnetic field in the senselayer.

FIG. 3a is a schematic representation of another embodiment of thecladded write conductor of the present invention.

FIG. 3b is a greatly enlarged portion of the cladded write conductor ofFIG. 3a illustrating the components of the magnetic field in the senselayer.

FIG. 4 is a perspective view of an MRAM device using the presentinvention.

FIGS. 5a and 5 b illustrate alternate sense layer shapes.

FIGS. 6a-6 d illustrate possible pole designs for the present invention.

FIGS. 7a-7 g illustrate a process for forming one embodiment of thecladded write conductor of the present invention.

FIG. 8 illustrates an alternate process step for forming a differentconstruction of the cladded write conductor of the present invention.

FIG. 9 illustrates a memory cell traversing a cladded write conductorhaving non-planarized pole extensions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings which form a part hereof,and in which is shown by way of illustration specific embodiments inwhich the invention may be practiced. It is to be understood that otherembodiments may be utilized and structural or logical changes may bemade without departing from the scope of the present invention. Thefollowing detailed description, therefore, is not to be taken in alimiting sense, and the scope of the present invention is defined by theappended claims.

In FIG. 1a, a prior art write line structure 10 is schematicallyrepresented. Magnetic field keeper 11 is positioned such that write line12 is covered on its back surface 14 and side surfaces 16 by magneticfield keeper 11. The poles 18 of magnetic field keeper 11 areapproximately flush with the front surface 20 of write line 12 andseparated by a distance Dpo. Sense layer 22 of the magnetic memory cellis positioned adjacent the front surface 20 of write line 12, such thatsense layer 22 of the memory cell is positioned above and between poles18 of magnetic field keeper 11.

The portion of FIG. 1a enclosed by dashed circle 30 is shown greatlyenlarged in FIG. 1b. The magnetic field emanating from poles 18 ofmagnetic field keeper 11 is represented by vector 32. As illustrated,magnetic field vector 32 includes both a longitudinal component 34 and aperpendicular component 36. The longitudinal component 34 is directedalong the easy axis of the sense layer 22 and contributes to theswitching of the magnetization in the sense layer 22. Because thestrength of the magnetic write field is inversely proportional to thedistance D_(P0) between poles 18, for a given current the strength ofthe write field is limited by the width of the write line 12. The priorart structure 10 is thus limited in its ability to compensate foreverdecreasing memory cell sizes and the need for a stronger write fieldfrom the word lines.

The present invention utilizes a novel cladding structure about thewrite line conductors to decrease the distance between the poles of theflux concentration means, and thereby produce a greater write field fora given current and write line width. The present invention is notlimited by the width of the write line, as in the prior art.

FIG. 2a shows one embodiment of the present invention in which a writeconductor 40 having a width W_(C1) is surrounded by cladding 42 on itsback surface 44, side surfaces 46, and a portion of its front surface48. Cladding 42 terminates at poles 50 which are positioned along frontsurface 48 and away from side surfaces 46. Poles 50 are spaced from eachother by a distance D_(P1) which is less than W_(C1). The sense layer 52of the magnetic memory cell has a width W_(S1) which is less than D_(P1)and is positioned directly between poles 50. As discussed below withrespect to FIGS. 3a and 3 b, the sense layer 52 may also have a widthgreater than D_(P1).

The portion of FIG. 2a enclosed by circle 60 is shown in FIG. 2b. Themagnetic field emanating from poles 50 of cladding 42 is represented byvector 62. As illustrated, magnetic field vector 62 has only alongitudinal component and no perpendicular component. Thus, in theembodiment of FIGS. 2a and 2 b the entire magnetic field generated bywrite conductor 40 is utilized to switch the orientation ofmagnetization of sense layer 52.

The construction as shown in FIGS. 2a and 2 b provides multipleadvantages over the prior art. First, poles 50 are positioned closer toeach other than allowed by prior art devices. That is, D_(P1) is lessthan W_(C1). This allows a stronger write field to be created for agiven current and write line width. Second, because sense layer 52 ispositioned directly between poles 50, there is no significantperpendicular component of the magnetic field. Rather, the entiremagnetic field is directed in the longitudinal direction. Thus, astronger magnetic field may be formed in the sense layer 52 for a givencurrent in write line 40. Alternately, a lower current may be providedin write line 40 for a desired magnetic field strength.

FIG. 3a shows another embodiment of the present invention in which awrite conductor 70 having a width W_(C2) is surrounded by cladding 72 onits back surface 74, side surfaces 76, and a portion of its frontsurface 78. Cladding 72 terminates at poles 80 which are positionedadjacent to the front surface 78 and away from the side surfaces 76.Poles 80 are spaced from each other by a distance D_(P2) which is lessthan the width W_(C2) of the conductor 70. This confers the advantagethat the poles 80 are positioned closer to each other than allowed byprior art devices (i.e., the distance between poles 80 is less than thewidth of the write line 70), thereby allowing a stronger write field tobe created for a given current and write line width. In this embodiment,a sense layer 82 having a width W_(S2) is positioned above the poles 80,such that poles 80 are positioned between front surface 78 and senselayer 82. Width W_(S2) of sense layer 82 is greater than the spacingD_(P2) between poles 80, which is important for reasons elaborated uponbelow.

The portion of FIG. 3a enclosed by circle 90 is shown greatly enlargedin FIG. 3b. The magnetic field emanating from poles 80 of cladding 72 isrepresented by vector 92. The magnetic field vector 92 has both alongitudinal component 94 and a perpendicular component 96, as in theprior art devices discussed above. However, the construction of FIGS. 3aand 3 b has the advantage over the prior art devices in that a highermagnitude magnetic field will be created in a narrower region of senselayer 82. That is, the construction shown in FIGS. 3a and 3 b mimics theeffect of write conductor 70 being narrower than sense layer 82, withoutW_(C2) actually being less than W_(S2).

The benefits of write conductors being smaller in dimension than thesense layer of the memory cell are described in U.S. Pat. No. 6,236,590to Bhattacharyya et al., which is herein incorporated by reference.Specifically, the advantages of the write conductors having dimensionssmaller than the dimensions of the sense layer include but are notlimited to: improved coupling of a write magnetic field with the senselayer so that the write magnetic field is not wasted or reduced due tomisalignments between the sense layer and the write conductor; reducedpossibility of misalignments between the write conductors and the senselayers; elimination or reduction of leakage magnetic fields that mayinterfere with adjacent memory cells; an increase in the magnitude ofthe magnetic field for a given current; and the ability to generate amagnetic field necessary to rotate the orientation of magnetization ofthe sense layer with a reduced magnitude of current, thereby reducingpower consumption by the MRAM device.

The embodiment of the invention shown in FIGS. 3a and 3 b provides allof the advantages enumerated above, without requiring an actualreduction in size of the write conductor. The ability to mimic theeffects of the write conductor being narrower than the sense layer,without actually reducing the dimensions of the write conductor orincreasing the size of the sense layer, is advantageous for severalreasons. First, manufacturing write conductors of ever decreasing sizebecomes increasingly difficult and expensive. Second, decreasing thesize of the write conductors may introduce undesirable consequenceswhich the offset the benefits of the write conductors being smaller indimension than the sense layers. Specifically, reducing the dimensionsof the write conductor results in a corresponding increase in resistanceof the conductor. The increased resistance of the write conductorintroduces the need for a higher voltage source to drive the currentthrough the write conductor. Also, a higher resistance in the writeconductor increases the amount of heat generated by the MRAM device,which may prove difficult to dissipate. Decreasing the area of the writeconductor also increases the current density in the write conductor,which may lead to undesirable electromigration.

Although the examples of the present invention as shown in FIGS. 2a, 2b, 3 a and 3 b illustrate only a single write conductor (that is, onlythe word line or the bit line), it will readily be recognized by thoseskilled in the art that the principles discussed above mayadvantageously be used with both word lines and bit lines in a magneticrandom access memory, either in combination or alone. As shown in FIG.4, a magnetic memory cell 100 having a data storage layer 101 ispositioned between a first conductor 102 and a second conductor 104. Thefirst conductor 102 has a width W_(C3) and extends in a first direction106, and the second conductor 104 has a width W_(C4) and extends in asecond direction 108. In a preferred embodiment, the first and seconddirections 106, 108 are generally orthogonal to each other. However, theinvention described herein is equally applicable when the first andsecond directions 106, 108 are not orthogonal. The data storage layer101 has a first layer width W_(S3) in the first direction 106, and asecond layer width W_(S4) in the second direction 108. The data storagelayer 101 has an easy axis which is generally aligned with the seconddirection 108. It will be noted that in FIG. 4, data storage layer 101and cladding 110 are positioned about first and second conductors 102,104 as exemplified above in FIGS. 3a and 3 b. However, data storagelayer 101 and cladding 110 may alternately be configured as describedabove with respect to FIGS. 2a and 2 b.

In all of the examples given above, cladding 42, 72, 110 preferably iscomprised of high permeability ferromagnetic materials. Examples ofpreferred cladding material alloys are NiFe, CoFe, Co, Fe, FeN, andamorphous Co-based alloys (CoZrNb, CoTaNb, CoHfNb). Those skilled in theart will recognize that other materials may also be suitable for thepurposes intended. The cladding materials forming the pole extensions onthe front surface of the write conductors need not be the same as thecladding materials on the other three sides of the conductor. Thethickness of the cladding layers is preferably in the range of 1 to 50nm, and more preferably in the range of 5-15 nm.

The sense layers 52, 82, 101 described above can be magnetoelectricdevices that include but are not limited to spin dependent tunnelingdevices, spin valve devices, and giant magnetoresistive devices.Further, although the sense layers 52, 82, 101 are illustratedheretofore as having rectangular shapes, the sense layers 52, 82, 101may have shapes that include but are not limited to a rectangular shape,a polygon shape 101′, and an arcuate shape 101″, as illustrated in FIGS.5a and 5 b, respectively.

The design of the poles 50, 80 may be selected so as to maximize themagnetic field for a given current. Examples of preferred pole designsare shown in FIGS. 6a-6 d, by way of the example only. Each of theillustrated pole designs act to sharpen the edge of the poles so as tomore highly concentrated the magnetic field emanating from the poles.Those skilled in the art will recognize a multitude of additional poleshapes which will also serve for the intended purpose.

The embodiments described in this invention may be fabricated by thoseskilled in the art using known methods of deposition, lithography, etchand planarization common to semiconductor manufacturing.

It is recognized that one implementation of this invention may requirepatterned features with lateral dimensions less than the minimum featuresize λ allowed by the lithography system. Referring to FIG. 3a, forexample, the distance D_(P2) may be less than λ. A process forgenerating the gap between the poles of the cladding at sub-λ dimensionsis described below with reference to FIGS. 7a-7 g.

First, an assembly of planarized conductors 120 having cladding 122 isfabricated within a matrix of dielectric 124, as shown in FIG. 7a.Damascene processing may be employed to create such conductors. Cladding122 preferably includes a layer of ferromagnetic material, and may alsoinclude a barrier layer between the layer of ferromagnetic material andthe conductor 120. Next, a layer of ferromagnetic material 126 that willserve as pole extensions is deposited, followed by a dielectric layer128. Photolithographic and etch processes are used to remove both thedielectric and ferromagnetic layers 128, 126, respectively, in regions130 (defined by photoresist 129) between the cladded conductors 120, asshown in FIG. 7b. A second dielectric layer 132 is deposited over thepatterned films, and the two dielectric layers 128, 132 are thenplanarized to form the structure of FIG. 7c. Preferential etching of thefirst dielectric 128 leaves the second dielectric 132 between theconductors 120. Conformal deposition of a third dielectric 134 createsthe topography illustrated in FIG. 7d. Exposing this structure to ahighly anisotropic etch removes dielectric only in the verticaldimension, allowing a narrow via 136 to be formed down to theferromagnetic material 126. At this point the ferromagnetic material 126is etched to create the pole extensions 138 and gap D_(P) between thepoles 140, which can be less than λ (refer to FIG. 7e).

If a planarized surface is desired, a fourth dielectric layer 142 isdeposited to fill the via 136 regions (FIG. 7f) and then planarized(FIG. 7g). Alternatively, the dielectric films remaining after step 7 ecan be etched to create the cladded conductors of FIG. 8. Traditionaldeposition and patterning methods can then be employed to create thememory cell on top of these structures.

Referring to FIG. 3A, the magnetic sense layer 82 in the memory cell canbe either in direct contact with the pole extensions 81, or physicallyseparated from the pole extensions by an intervening layer.Additionally, it is not a requirement that the pole extensions 81 beplanarized, as indicated in FIG. 7g, prior to deposition of the memorycell or sense layer.

The thickness of the pole extensions may be as little as 1 nm, ispreferably on the order of 1 to 50 nm, and more preferably on the orderof 5 to 15 nm. A memory cell 142 traversing non-planarized poleextensions 138 is shown in FIG. 9. It is also noted that neither thememory cell 142 (including the sense layer) nor the gap D_(P) betweenthe pole extensions 138 have to be centered above the conductormaterial.

Although specific embodiments have been illustrated and described hereinfor purposes of description of the preferred embodiment, it will beappreciated by those of ordinary skill in the art that a wide variety ofalternate and/or equivalent implementations may be substituted for thespecific embodiments shown and described without departing from thescope of the present invention. Those with skill in theelectromechanical and electrical arts will readily appreciate that thepresent invention may be implemented in a very wide variety ofembodiments. This application is intended to cover any adaptations orvariations of the preferred embodiments discussed herein. Therefore, itis manifestly intended that this invention be limited only by the claimsand the equivalents thereof.

What is claimed is:
 1. A write line structure for a magnetic memorydevice having a magnetic field sensitive memory cell, comprising: awrite conductor having a front surface adjacent the memory cell, a backsurface and two sides surfaces; a cladding layer adjacent the backsurface, the two sides surfaces and a portion of the front surface ofthe write conductor, the cladding layer including a layer of magneticmaterial, wherein the cladding layer adjacent the front surface of thewrite conductor forms two pole pieces adjacent to the front of the wireconductor, and wherein the pole pieces are positioned between the frontsurface of the wire conductor and the magnetic memory cell.
 2. The writeline structure of claim 1, wherein the magnetic memory cell has a widthgreater than the spacing between the pole pieces.
 3. The write linestructure of claim 2, wherein the magnetic memory cell is spaced fromthe pole pieces.
 4. The write line structure of claim 2, wherein themagnetic memory cell is in contact with the pole pieces.
 5. A write linestructure for a magnetic memory cell, comprising: a write conductorhaving a front surface facing the memory cell, a back surface and twosides surfaces, the write conductor having a first width; a claddinglayer disposed adjacent a portion of the front surface of the writeconductor, the cladding layer terminating at first and second polesadjacent the front surface of the write conductor, the first and secondpoles separated from each other by a second width; and a data storagelayer operatively positioned adjacent the cladding layer, the datastorage layer having a third width; wherein the second width is lessthan the first width and wherein the second width is less than the thirdwidth.
 6. A write line structure for a magnetic memory cell, comprising:a write conductor having a front surface facing the memory cell, a backsurface and two sides surfaces, the write conductor having a firstwidth; a cladding layer disposed adjacent a portion of the front surfaceof the write conductor, the cladding layer terminating at first andsecond poles adjacent the front surface of the write conductor, thefirst and second poles separated from each other by a second width; anda data storage layer operatively positioned adjacent the cladding layer,the data storage layer having a third width; wherein the second width isless than the first width; and wherein the poles are tapered.
 7. A writeconductor layout structure for a magnetic memory cell, comprising: afirst conductor having a first width; a second conductor having a secondwidth; a data storage layer operatively positioned between the firstconductor and the second conductor and having a first layer width in afirst direction and a second layer width in a second direction, thefirst and second conductors crossing the data storage layer insubstantially the first and second directions, respectively; a firstcladding layer disposed about the first conductor and terminating at afirst set of poles between the first conductor and the data storagelayer, the first set of poles separated by a first spacing; and a secondcladding layer disposed about the second conductor and terminating at asecond set of poles between the second conductor and the data storagelayer, the second set of poles separated by a second spacing; whereinthe first spacing between the first set of poles is less than the firstwidth of the first conductor and is less than the second layer width ofthe data storage layer.
 8. The write conductor layout structure of claim7, wherein the second spacing between the second set of poles is lessthan the second width of the second conductor and is less than the firstlayer width of the data storage layer.
 9. The write conductor layoutstructure of claim 7, wherein a selected one of the first direction orthe second direction is co-linear with an easy axis of the data storagelayer.
 10. The write conductor layout structure of claim 7, wherein thedata storage layer is a magnetoelectric device selected from the groupconsisting of a spin dependent tunneling device, a spin valve device,and a giant magnetoresistive device.
 11. The write conductor layoutstructure of claim 7, wherein the first and second directions aresubstantially orthogonal to each other such that the first conductor andthe second conductor cross the data storage layer in substantiallyorthogonal relation to each other.
 12. A method for concentrating amagnetic field in a sense layer of a magnetic memory cell, comprising:forming a cladding layer on a write conductor having a front surface, aback surface and two sides surfaces, the cladding including a layer ofmagnetic material disposed adjacent the back, side and front surfaces ofthe write conductor, the cladding layer terminating at first and secondpoles adjacent the front surface of the write conductor; and placing adata storage layer adjacent the first and second poles of the cladding,wherein the first and second poles are positioned between the frontsurface of the write conductor and the data storage layer.
 13. Themethod of claim 12, wherein the poles are separated from each other by adistance less than a width of the data storage layer.